A seat belt buckle devised to maximize holding capability as well as to improve the cost and ease of manufacture is disclosed in the U.S. Pat. No. 4,617,705 issued to James R. Anthony and Allan R. Lortz. The buckle includes a reinforcement plate mounted to and between an upper and lower housing containing a spring biased pawl engageable with a seat belt tongue. The pawl is held captive between the lower housing and the reinforcement plate, and is biased upwardly against the plate by a pair of springs. A push button is slidably mounted to the upper housing and has a pair of legs extending downwardly through the plate to contact and move the pawl downwardly to disengage the pawl from the tongue. An additional spring mounted between the push button and reinforcement plate requires force above a predetermined level to move the button downwardly to disengage the pawl from the tongue. In many cases, the seat belt tongue is split into two separate tongues for attachment respectively to a seat belt and a shoulder harness. In order to increase the fit and engagement between the buckle and the tongue or pair of tongues inserted into the buckle and to ensure the tongues are not mounted upsdie down in the buckle, it is custom to provide a pair of flanges extending outwardly from the reinforcement plate to engage and provide a stop means limiting motion including pivotal motion of the tongue(s).
In the case of a belt buckle engageable with a pair of tongues, it is desirable to provide a buckle that will not lockingly engage when only a single tongue is inserted into the buckle. We have therefore devised a belt buckle, disclosed in our U.S. Pat. Nos. 5,023,981 and 5,038,446, which will lockingly engage the tongues only when both tongues are fully inserted therein. However, simultaneously inserting the dual tongues into the buckle in order to trigger the latching mechanism is not always a trouble-free exercise. For instance, one solution was to provide dual tongues which interlocked together as in tongue 100 shown in FIG. 1 of the present application. Dual interlocking tongues essentially become a single tongue when interlocked together before being inserted into the buckle. Dual interlocking tongues suffer from a number of disadvantages not least of which is the difficulty in connecting the interlocking features when hands are needed for other tasks such as keeping a squirming infant properly positioned in a child restraint seat while the restraints are being secured. FIG. 9 of the present application illustrates another dual tongue system 300 that has mating surfaces to aid the user in simultaneously inserting dual tongues into the buckle. While this type of dual tongue can substantially eliminate some of the problems encountered in interlocking dual tongues, these designs still have the drawback that the dual tongues can slide relative to one another, and therefore can result in some difficulty inserting both tongues simultaneously into the buckle in order to trigger the latching mechanism.
Another system known in the art for securing at least two webs to a single buckle is to provide one of the webs with an ordinary tongue and the other with a plastic or metallic loop in place of a tongue. The loop is sized large enough to receive the tongue bar of the tongue but is too small to slip over the handle portion of the tongue. The webs are secured to the buckle by advancing the tongue bar of the tongue through the loop and then advancing the tongue bar into the buckle to trigger the latching mechanism. In this way, the web having the loop attachment is trapped between the buckle and the handle portion of the tongue. Like the prior art just discussed, this type of tongue and loop system suffers from the disadvantage of not always being easily assembled before the webs are secured to the belt buckle.
What is needed is a pair of dual interactive tongues that retain the advantages of both interlocking dual tongues and those having other mating features but does not suffer from their respective disadvantages nor introduce new drawbacks to a dual tongue buckle system.